Effects of nicotine on epithelial nephron cells in culture

Long-term effects of nicotine on cultured cells derived from defined segments of the nephron were studied in vitro. Nicotine was added during a 10-day incubation period to a defined nephron culture medium (NCM) which had been supplemented with one of the following: fetal calf serum (FCS), dexamethasone (D), aldosterone (A), or epidermal growth factor (EGF). Thymidine incorporation (10^-15 mmol/10³ cells) into cultured cells of the cortical thick ascending loop of Henle (TAL) and of the cortical collecting tubule (CT) was inhibited by nicotine (5 · 10¹ ng/ml) when incubated in NCM only; the presence of FCS or of D (10^-8 M) or of D and EGF (25 ng/ml) prevented this inhibitory effect. Nicotine at a concentration of 5 · 10² ng/ml was inhibitory in TAL and CT even in the presence of FCS. Na-K-ATPase activity (pmol/10³ cells · min^-1) was stimulated significantly by D when compared with NCM; nicotine (5 · 10² ng/ml) prevented this inductive effect. Transepithelial voltage was 27.1 ± 6 (mV) after incubation with A (10^-9 M), and 7.2 ± 4.1 when incubated with A and nicotine (5 · 10² ng/ml). These data indicate that nicotine may interfere with factors stimulating cell proliferation, sodium pump enzyme activity, and ion flux (voltage). An effect of nicotine on the cellular Na-entry step would be consistent with the data.